On 11 Mar 2010, at 20:34, Pierre-Antoine Champin wrote:
Is it correct that all representations must have consistent fragment
identifiers in order to be considered equivalent?
A fragment identifier should not identify different things in
different
representations. (Though it may be unrepresented in some or all of
the
representations.)
Is that so?
If I recall correctly the URI RFC (no internet when writing the mail,
sorry), the semantics of fragments identifiers depends on the
retrieved
content-type.
Correct, see [1]: “The semantics of a fragment identifier are defined
by the set of representations that might result from a retrieval
action on the primary resource. The fragment's format and resolution
is therefore dependent on the media type [RFC2046] of a potentially
retrieved representation, even though such a retrieval is only
performed if the URI is dereferenced.”
So why would they *have* to identify the same thing?
You just have to read one paragraph down:
“If the primary resource has multiple representations, as is often the
case for resources whose representation is selected based on
attributes of the retrieval request (a.k.a., content negotiation),
then whatever is identified by the fragment should be consistent
across all of those representations. Each representation should either
define the fragment so that it corresponds to the same secondary
resource, regardless of how it is represented, or should leave the
fragment undefined (i.e., not found).”
Best,
Richard
[1] http://www.ietf.org/rfc/rfc3986.txt
That being said, I agree it sounds like a good practice. Especially if
you consider an RDF/XML and a Turtle representation of the same RDF
graph... If their fragment identifier were not consistent, that
would be
a serious headache... But is this rule written somewhere?
pa
